Photovoltaic module mounting clip with integral grounding

ABSTRACT

An electrically conductive mounting/grounding clip, usable with a photovoltaic (PV) assembly of the type having an electrically conductive frame, comprises an electrically conductive body. The body has a central portion and first and second spaced-apart arms extending from the central portion. Each arm has first and second outer portions with frame surface-disrupting element at the outer portions.

CROSS-REFERENCE TO OTHER APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/681,972 filed on 5 Mar. 2007, attorney docket number PWRL 1044-2,having the same title as this application, which application claims thebenefit of U.S. Provisional Patent Application No. 60/780,819 filed on 9Mar. 2006, attorney docket number PWRL 1044-1, and U.S. ProvisionalPatent Application No. 60/821,869 filed on 9 Aug. 2006, attorney docketnumber PWRL 1045-1, the disclosures of which are incorporated byreference for all purposes.

STATE SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with State of California support underCalifornia Energy Commission Agreement Number 500-04-022. The EnergyCommission has certain rights to this invention.

BACKGROUND OF THE INVENTION

This invention generally relates to the mounting of framed photovoltaic(PV) modules atop roofs and other support structures, where positivemechanical securement of the modules to the supporting base or structureis desirable and electrical grounding of accessible metal components,such as the PV module frame and ancillary mounting components, isrequired. Known combined mounting/grounding devices require a specialflange on the outside of the photovoltaic module frame and a speciallydesigned clip or other attachment device. Therefore, conventionalcombined mounting/grounding devices are limited to use with specificmodule frame geometries.

BRIEF SUMMARY OF THE INVENTION

A first example of an electrically conductive mounting/grounding clip,for use with PV assemblies of the type having electrically conductiveframes separated by gaps, comprises an electrically conductive bodyhaving a central portion and first and second spaced-apart armsextending generally perpendicular to the central portion. Each arm hasan outer portion, each outer portion having first and second outer ends.The clip also has a frame surface-disrupting element at each outer end.The central portion defines a plane. The frame surface-disruptingelements point towards the plane. In some examples the framesurface-disrupting elements comprise frame-surface-penetrating teeth. Insome examples each arm extends from the central portion at an acuteangle to the plane, such as 80-88°.

A second example of an electrically conductive mounting/grounding clip,for use with an array of PV assemblies of the type having electricallyconductive frames separated by gaps, includes an electrically conductivebody. The body comprises a central portion and first and secondspaced-apart, generally T-shaped arms extending from the centralportion. Each arm extends from the central portion at an acute angle tothe plane. Each arm has an outer portion, each outer portion havingfirst and second outer ends. A plurality of frame surface-disruptingelements are at each outer end. The frame surface-disrupting elements ofeach arm are oriented in a direction generally parallel to a lineconnecting the outer ends of said arm. The central portion defines aplane and the frame surface-disrupting elements point towards the plane.

An example of an electrically conductive mounting/grounding clipassembly, for use with an array of PV assemblies of the type havingelectrically conductive frames separated by gaps, includes anelectrically conductive clip and a second member. The clip includes acentral portion and first and second spaced-apart arms extendinggenerally perpendicular to the central portion. Each arm has an outerportion and each outer portion has first and second outer ends. A framesurface-disrupting element is it each outer end. The central portiondefines a plane and the frame surface-disrupting elements point towardsthe plane. The clip assembly also includes means for (1) biasing theframe surface-disrupting elements of the clip against electricallyconductive frames of adjacent PV assemblies thereby electricallyconnecting the frames to one another through the clip, and (2) securingthe clip to the second member.

An example of a PV installation includes a support, first and second PVassemblies and an electrically conductive mounting/grounding clipassembly for use with the first and second PV assemblies. The first andsecond PV assemblies are of the type having electrically conductiveframes separated by a gap, the frames each having an upper surface. Theclip assembly comprises an electrically conductive clip. The clipincludes a central portion and first and second spaced-apart, generallyT-shaped arms extending generally perpendicular to the central portion.The central portion and arms define an access region accessible fromabove. Each arm has an outer portion, each outer portion having firstand second outer ends. At least one frame surface-disrupting element isat each outer end. The central portion defines a plane. The clipassembly also includes a second member, positioned generally beneath thefirst and second PV assemblies and supported by the support, and anelongated connection member. The elongated connection member secures theclip to the second member and is extendable within the gap between theelectrically conductive frames so that the frame-disrupting element canbe forced against the electrically conductive frames therebyelectrically connecting the frames to one another through the clip. Thecentral portion comprises a hole and the elongated connection membercomprises a connection element passing through the hole. The connectionelement has an upper end located completely within the access region andbelow the upper surface. In some examples the frame comprises anelectrically non-conductive surface and the frame surface-disruptingportion comprises surface-penetrating teeth. In some examples the clipassembly further comprises means for preventing the clip from tippingaway from the frame as the clip is biased against the frame by theelongated connection member. In some examples the connection element mayinclude a threaded member, such as a bolt or a stud.

A third example of an electrically conductive mounting/grounding clip,for use with a PV assembly of the type having an electrically conductiveframe, comprises an electrically conductive body. The body has a centralportion and first and second spaced-apart arms extending generallyperpendicular to the central portion. Each arm has an outer portion witheach outer portion having an outer end. A plurality of framesurface-disrupting elements are at each outer end. The central portiondefines a plane with the frame surface-disrupting elements pointingtowards the plane. In some examples each arm extends from the centralportion at an acute angle to the plane.

A second example of an electrically conductive mounting/grounding clipassembly, for use with a PV assembly of the type having electricallyconductive frame, includes an electrically conductive clip and a secondmember. The clip comprises a central portion and first and secondspaced-apart arms extending from the central portion. Each arm has anouter portion with each outer portion having an outer end. A framesurface-disrupting element is it each outer end. The central portiondefines a plane and the frame surface-disrupting elements point towardsthe plane. The clip assembly also includes means for (1) biasing theframe surface-disrupting elements of the clip against the electricallyconductive frame of an adjacent PV assembly thereby electricallyconnecting the frame to the clip, and (2) securing the clip to thesecond member. The clip assembly further includes means for preventingthe clip from tipping away from the frame as the clip is biased againstthe frame by the biasing and securing means.

A second example of a PV installation comprises a support, a PV assemblyand an electrically conductive mounting/grounding clip assembly for usewith the PV assembly. The PV assembly is of the type having anelectrically conductive frame, the frame having an upper surface. Theclip assembly comprises an electrically conductive clip. The clipcomprises a central portion and first and second spaced-apart armsextending generally perpendicular to the central portion. The centralportion and arms define an access region accessible from above. Each armhas an outer portion with each outer portion having an outer end. Atleast one frame surface-disrupting element is at each outer end. Thecentral portion defines a plane. The frame surface-disrupting elementpoints towards the plane. The clip assembly also includes a secondmember positioned generally beneath the PV assembly and supported by thesupport. The clip assembly further includes an elongated connectionmember securing the clip to the second member so that theframe-disrupting element can be forced against the electricallyconductive frame thereby electrically connecting the frame to the clip.The central portion has a hole and the elongated connection membercomprises a connection element passing through the hole. The connectionelement has an upper end located completely within the access region andbelow the upper surface. The clip assembly further includes means forpreventing the clip from tipping away from the frame as the clip isbiased against the frame by the elongated connection member.

Various advantages, discussed below, accrue through the use of differentexamples of the invention. The clip assemblies can provide both amounting and electrical grounding function. This saves considerablematerial and labor costs as compared to the conventional approach ofrunning a grounding wire between all PV modules. The clips are can alsobe less expensive than typical tinned copper grounding lugs. The clipscan be easily secured to the modules from above, unlike approaches whichrequire the use of mounting and grounding holes in the module frame;such holes have limited accessibility, especially after installation.This reduces installation and maintenance costs. The clip assembly canbe module neutral; that is, it can be used on any framed PV module inwhich at least portions of the frame are electrically conductive forgrounding the PV module. Examples of the invention also do not requireany special construction of the module frame, such as external flangesspecific to a particular module manufacturer. The geometry of the clipassembly can comprise a direct connection for grounding as required byUnderwriters Laboratories (UL) as opposed to some other approaches,where the grounding points are not directly connected to the moduleframe by the mounting bolt or stud. Some examples of the clip assemblyare amenable to use as a grounding device independently from itsfunction as a mounting device, if desired.

Other features, aspects and advantages of the present invention can beseen on review of the figures, the detailed description, and the claimswhich follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view of a clip assembly;

FIG. 1A is an enlarged partial side view of the clip of FIG. 1;

FIG. 2 is an assembled isometric view of the clip assembly of FIG. 1;

FIG. 3 is an enlarged cross-sectional view of the clip assembly of FIG.2 shown secured to adjacent PV assemblies;

FIG. 4 is a simplified overall view of two adjacent PV assembliessecured to one another using the clip assembly FIGS. 1-3;

FIGS. 5-8 illustrate different types of clip assemblies used withdifferent types of support structures;

FIG. 9 is an overall view of a peripheral clip assembly;

FIG. 10 is a cross-sectional view of the clip assembly of FIG. 9;

FIG. 11 shows a clip assembly of FIGS. 1 and 2 used at the periphery ofa PV array with a spacer;

FIGS. 12 and 13 are exploded isometric and isometric views of aninternal clip assembly; and

FIG. 14 is a cross-sectional view showing the clip assembly of FIG. 13secured to the internal lip of the frame of a PV assembly.

DETAILED DESCRIPTION OF THE INVENTION

The following description will typically be with reference to specificstructural embodiments and methods. It is to be understood that there isno intention to limit the invention to the specifically disclosedembodiments and methods but that the invention may be practiced usingother features, elements, methods and embodiments. Preferred embodimentsare described to illustrate the present invention, not to limit itsscope, which is defined by the claims. Those of ordinary skill in theart will recognize a variety of equivalent variations on the descriptionthat follows. Like elements in various embodiments are commonly referredto with like reference numerals.

FIG. 1 is an exploded isometric view of one example of a clip assembly10 made according to the invention. Assembly 10 includes a clip 12secured to a second member 14 by a bolt 16. Second member 14 includes abase 18, typically of extruded aluminum or some other appropriatematerial, and a sealant 20 secured to the lower surface 22 of base 18.Sealant 20 is typically in the form of a butyl tape about 3 mm thick.Base 18 has a pair of raised portions 24 defining a gap 26 therebetween.Gap 26 extends down to a central region 28 of base 18, central region 28having a number of threaded holes 30 formed therein for receipt of bolt16. Base 18 also has a pair of flanges 32 having a number of mountingholes 34 used to secure second member 14 to a mounting surface, such asa roof. Bolt 16 passes through a central opening 36 in clip 12, througha hole 38 formed in a spacer 40, through gap 26, and into a threadedhole 30. Other types and configurations for base 18, such as that shownin provisional patent application No. 60/821,869, may also be used.

FIG. 2 shows clip assembly 10 in an assembled form while FIG. 3illustrates clip assembly 10 of FIG. 2 securing adjacent PV assembliesto second member 14. FIG. 4 is a simplified overall view illustratingtwo clip assemblies 10 engaging adjacent PV assemblies 50 in the gap 58between the PV assemblies. Clip assemblies 10 are commonly referred toas interior clip assemblies when used between adjacent PV assemblies.

Clip 12 is a generally U-shaped structure having a central portion 42,through which central opening 36 is formed, and a pair of upstandingarms 44. Arms 44 and central portion 42 define an access region 45.Access region 45 is accessible from above to provide clear access tobolt 16 thus facilitating the use of clip assembly 10. Arms 44 includeextensions 46 having downwardly extending teeth 48. As shown in FIG. 3,clip assembly 10 is used with PV assemblies 50 of the type havingelectrically conductive frames 52 surrounding PV panels 54. As can beseen in FIGS. 2 and 3, the head of bolt 16 is located completely withinaccess region 45 and is located below the top surface of frame 52 of PVassembly 50. In addition, the generally T-shaped configuration of arms44 with downwardly facing teeth 48 provide for a low profile structure.This low profile structure creates a cleaner, less cluttered appearanceand also minimizes shading of PV panel 54.

Frames 52 have an upper, circumferentially extending edge 56 which areengaged by teeth 48 of clip 12. Frame 52 is typically anodized aluminumand thus has a non-conductive outer surface. Frame 52 may also haveother types of non-conductive outer surfaces, such as a painted outersurface. To ensure good electrical contact between clip 12 and frame 52,teeth 48 act as surface-disrupting elements. The serrated teeth or otherstructure cuts through any nonconductive material on frame 52 therebycreating a positive electrical connection with clip 12, and via bolt 16,to second member 14. This helps to ensure good grounding between frames52 of adjacent PV assemblies 50 through clip 12. Othersurface-disrupting methods could also be used, such as causing clip 12to slide against and score a portion of frame 52 or through the use ofother types of surface-disrupting structures or procedures.

In the example of FIGS. 1-3, three teeth 48 are used at each extension46 of arms 44. The use of a number of points 44 at each extension 46allows some adjustment in the position of clip 12 relative to frame 52,thus facilitating installation. Teeth 48 are oriented to be generallyparallel to a line connecting extensions 46 of each arm 44 and thusgenerally perpendicular to the adjacent frame 52.

Arms 44 are preferably not perpendicular to central portion 42. In thedisclosed example, arms 44 extend inwardly over central portion 42 todefine an included angle 53, see FIG. 1A. Included angle 53 is an acuteangle and typically ranges from 80-88°, and is about 83° in thedisclosed example. This helps to strengthen clip 12 because arms 44 willtend to straighten out under load. Another advantage with the angulationof arms 44 is that doing so results in more of a point contact by teeth48 with frame 52. This can be for two primary reasons. The first reasonis that teeth 48, for practical purposes, do not narrow down to a truepoint but rather to a line or edge, the length of which is as long asclip 12 is thick. Therefore, by angling arms 44, the ends of teeth 48first engage frame 52 to provide more of a point contact than a linecontact. The second reason is based upon the fact that manufacturingconstraints limit how sharp of an edge teeth 48 will exhibit. In someexamples, teeth 48 will exhibit a rounded edge so that if arms 44 wereperpendicular to central portion 42, teeth 48 would provide a generallycylindrical surface against frame 52.

Clip 12 also secures frame 52 to second member 14 by capturing the framebetween arms 44 of clip 12 and raised portions 24 of base 18. Spacer 40,as suggested in FIG. 3, helps to ensure adjacent PV assemblies 50 arelocated in a proper distance from one another. Spacer 40 is typicallymade of rubber or some other material including, for example, metal orcardboard, sized to be larger than the width of central portion 42,illustrated in FIG. 3. The size of spacer 40 is chosen so that when PVassemblies 50 expand during hot weather, or otherwise, PV assemblies 50have room to expand before contacting clip 12. This helps to preventdamage to PV panels 54, which could occur if PV assemblies 50 were topress directly against clip 12 during such thermal expansion. The use ofspacer 40 simplifies installation and by eliminating the need to use aspecial tool to ensure proper spacing of PV assemblies duringinstallation. Although the primary grounding created by clip 12 is fromframe 52 of one PV assembly 50 to frame 52 of an adjacent PV assembly,clip assembly 10 can also be used to provide grounding between PVassembly frames 52 and second member 14.

Clip assembly 10 provides a low profile mounting/grounding clip assemblyusable with a wide variety of PV assemblies of the type having anelectrically conductive circumferential frame having an exposed upperperipheral surface.

FIG. 5 illustrates a clip assembly 62 that uses a clip 64 similar toclip 12 but turned upside down with teeth 48 facing the oppositedirection so that they also pointed downwardly to engage frame 52 of PVassemblies 50. In addition, instead of using a central bolt 16, clipassembly 62 has a pair of L-shaped legs 66 extending downwardly from thearms 68 of clip 64. Second member 70 in this example has an upwardlyextending stud 72 passing through a hole, not shown, formed in the bentend 74 of each leg 66 with a nut 76 securing leg 66 to second member 70.

FIGS. 6 and 7 disclose further alternative embodiments similar to theembodiment of FIGS. 1-4, with a stud-type mount in FIG. 6 including astud 78 and a nut 80 and a bolt type mount in FIG. 7, and a differenttype of second member 82 supporting PV assemblies 50. The second memberssupporting PV assemblies 50 in FIGS. 5-7 are used to support sloped PVassemblies. This type of structure is shown in more detail in U.S.patent application Ser. No. 11/616,575, filed 27 Dec. 2006, entitledSupported PV Module Assembly, attorney docket number PWRL 1041-2, thedisclosure of which is incorporated by reference.

FIG. 8 shows a still further embodiment in which clip assembly 84includes a clip 64 connected to a pair of wind deflectors 86. Winddeflectors 86 may be of the type shown in the above referenced U.S.patent application Ser. No. 11/616,575. Clip assembly 84 also includesan L-shaped leg, not shown but similar to L-shaped leg 66 of FIG. 5, toprovide an electrical ground connection and a hold down or supportfunction for PV assemblies 50. A clip assembly can also be constructedto provide securement point(s) for other photovoltaic array components,such as a ballast pan, a visual shield, a fire shield, a wire tray orwire securement device, or a structural member. The securement points(s)may consist of a mounting hole, a threaded stud, or a snap fit device. Aclip assembly can also provide an attachment point for a conventionalgrounding lug or grounding wire. A particular securement point may alsoact as both a structural point and grounding point. Unlike clip assembly10, clip assembly 62, 84 of FIGS. 5 and 8 are most useful for use withPV assemblies 50 having frames 52 of a chosen height.

FIGS. 9 and 10 illustrate what is sometimes called a peripheral clipassembly 88. Unlike clip assemblies 10, 62 and 84, a peripheral clipassembly 88 is used to securely mount PV assembly 50 and may be used toground frame 52 to a support member. Similar types of installations areshown in U.S. Pat. Nos. 6,058,930 and 6,722,357, attorney docket numbersPWRL 1026-1 and 1027-1, the disclosures of which are incorporated byreference. In this embodiment perimeter clip 90 is secured to secondmember 92 using a bolt 16, an optional washer 94, and a standoff 96. Thelength of standoff 96 is determined by the height of frame 52. Standoff96 helps to prevent perimeter clip 90 from tipping away from frame 52when bolt 16 is tightened. Other types of spacers may also be used forthis purpose. Bolt 16 grounds frame 52 to second member 92, which inthis embodiment is a laterally-extending support mounted to a torquetube 98 of a tilted, tracking solar collector assembly. In this caseframes 52 of a row of PV assemblies 50 are grounded to one anotherthrough second member 92 and, optionally, to other rows of PV assembliesthrough torque tube 98 and other second members 92.

Clip assembly 10 of FIGS. 1 and 2 can be used at the periphery by using,for example, a spacer 100 located between the otherwise unusedextensions 46 of clip 12, see FIG. 11, and the second member 14. Spacer100 has a periphery 102 configured to accommodate frames 52 havingdifferent heights. Other types of variable-height of spacers, includingthreaded, telescoping spacers and spacers consisting of stacks ofindividual spacer elements, can also be used.

FIGS. 12-14 illustrate an internal clip assembly 106 designed as amodification of clip assembly 10 of FIGS. 1 and 2. Clip assembly 106includes a clip 108 and pieces of electrically insulatingadhesive-backed tape 110, 112. Tape 110 is secured to raised portions 24of base 18 to cover the end of upper surface 114 opposite clip 108. Tape112 is adhered to clip 108 as shown in FIGS. 12 and 13 to lie above gap26. Bolt 16 is tightened onto base 18 and then PV assembly 50 is securedto clip assembly 106 by sliding an internal lip 116 of frame 52 betweenclip 108 and base 18 engaging insulating tape 110, 112. In this exampleinternal clip assembly 106 acts to secure PV assembly 50 in place butdoes not provide a grounding function. In other examples internal clipassembly 106 could be configured to provide a grounding function as wellas a mounting function by, for example, causing a spike to pierce thesurface of lip 116 when the lip is inserted between clip 108 and base18. Tape 110, 112 helps to ensure the snug engagement of lip 116 betweenclip 108 and base 18 and also helps to reduce marring of the surface oflip 116. Although tape 110, 112 is in this example electricallyinsulating, it need not be.

The above-described embodiments have a clip assembly supported by asupport. The support is typically a commercial or residential roof orsupport frame member for a solar energy tracking system. The support canalso include trellises, carports, shade structures, and so forth. Theclip assembly can also be supported directly on the ground.

The clip assembly is preferably designed to withstand uplift and lateralloads as appropriate for the application. The clip materials are chosenfor required strength, corrosion resistance, and aesthetics.

During installation the mounting bolt may be torqued such that thethreaded member and the clip are pre-loaded above the maximum code windload plus an appropriate safety factor. This ensures a secure mechanicaland electrical connection in all field conditions and excludes moisturefrom the ground bond area at teeth 48 by creating a high pressureconnection zone around each point.

The use of threaded connections has been emphasized. However, othertypes of connections, such as a ratchet-type of connections andconnections using spring fingers, may also be used.

The above descriptions may have used terms such as above, below, top,bottom, over, under, et cetera. These terms are used to aidunderstanding of the invention are not used in a limiting sense.

While the present invention is disclosed by reference to the preferredembodiments and examples detailed above, it is to be understood thatthese examples are intended in an illustrative rather than in a limitingsense. It is contemplated that modifications and combinations will occurto those skilled in the art, which modifications and combinations willbe within the spirit of the invention and the scope of the followingclaims. Any and all patents, patent applications and printedpublications referred to above are incorporated by reference.

1. A clip for use with a photovoltaic (PV) assembly comprising: anelectrically conductive body comprising a central portion and first andsecond spaced-apart arms extending from the central portion; each armhaving first and second outer portions with frame surface-disruptingelement at the outer portions.
 2. The clip according to claim 1, whereinthe frame surface-disrupting elements point generally towards thecentral portion.
 3. The clip according to claim 1, wherein each armextends from the central portion at an acute angle to the centralportion.
 4. The clip according to claim 1, further comprising aplurality of said frame surface-disrupting elements at each outer end.5. The clip according to claim 1, wherein the frame surface-disruptingelements of each arm can be oriented in a direction generallyperpendicular to the PV assembly.
 6. The clip according to claim 5,further comprising means for preventing the clip from tipping away froma PV assembly as the clip is biased against the PV assembly by theelongated connection member.
 7. The clip according to claim 1, furthercomprising: a second member; and an elongated connection member securingthe clip to the second member so that the frame surface-disruptingelement can be forced against PV assemblies thereby electricallyconnecting the PV assemblies to one another through the clip.
 8. Theclip according to claim 7, wherein the central portion comprises anopening and the elongated connection member comprises a connectionelement passing through the opening, the connection element having anupper end, the upper end located completely within the access region andbelow the upper surface.
 9. The clip according to claim 8, whereinconnection element comprises a bolt, the upper end comprises a bolthead, and the second member comprises a threaded hole with which thebolt is threadably engaged.
 10. The clip according to claim 8, whereinconnection element comprises a stud extending from the second member andthe upper end comprises a threaded portion of the stud and a nutthreadably engaging the threaded portion.
 11. The clip according toclaim 1, wherein the frame surface-disrupting portion comprisessurface-penetrating teeth.
 12. The clip according to claim 1, whereinthe body is generally U-shaped.
 13. The clip according to claim 1,wherein the body comprises two arms and two outer portions for each arm.14. A clip for use with a photovoltaic (PV) assembly comprising: anelectrically conductive body comprising a central portion and first andsecond spaced-apart arms extending from the central portion; each armextending from the central portion at an acute angle to the centralportion; each arm having first and second outer portions with framesurface-penetrating elements at each outer portion; the framesurface-penetrating elements pointing generally towards the centralportion; and the frame surface-penetrating elements of each arm beingorientable in a direction generally perpendicular to the PV assembly.15. A PV installation comprising: a support; first and second PVassemblies of the type having electrically conductive frames separatedby a gap, the frames each having an upper surface; and a clip assemblyfor use with the first and second PV assemblies, the clip assemblycomprising: an electrically conductive clip comprising: an electricallyconductive body comprising a central portion and first and secondspaced-apart arms extending from the central portion; and each armhaving first and second outer portions with frame surface-disruptingelements at the outer portions.